A number of techniques are presently employed for detecting trace elements in gas samples. Mass spectrometers provide fairly rapid and sensitive measurements. However, such instruments are large, complex and very expensive and typically require an expert technician to operate and maintain. Liquid and gas chromotography and related electron capture techniques are somewhat less expensive although still costly and relatively reliable but, unfortunately, are quite slow. Response time is typically on the order of seconds to minutes. Where poisonous or otherwise hazardous elements are being monitored such a delay may be fatal. Another method utilizing chemically treated tape to detect phosphorous and arsenic containing compounds is also unacceptably slow, requiring up to thirty minutes to identify low concentrations of hazardous elements.
Infrared detection techniques exhibit a faster response time. However, they do not provide optimum sensitivity. Because so many elements absorb in the infrared range the elements of interest may be easily masked. Moreover, as with the mass spectrometer, infrared systems typically require considerable maintenance and a trained operator.